Molds and method of using the same for forming plus or minus lenses

Abstract

The present invention encompasses, in part, a method and apparatus for lens casting in which two molds, preferably formed of plastic, are interconnected or joined together via a ring to form a mold cavity having substantially the same dimensions of the lens to be formed therein. The invention is further directed to compositions and methods used in lens casting. In a first implementation the invention includes a mold having a ring having an interior periphery; a front mold formed of a plastic and having a lens-forming surface, an edge circumscribing the lens-forming surface that is sized to be complementarily received within a portion of the interior periphery of the ring, and a base having dimensions greater than the interior periphery; and a rear mold formed of a plastic and having a lens-forming surface.

1 . A casting device, comprising: 
 a. a ring having an interior periphery;    b. a front mold formed of a plastic and having a lens-forming surface, an edge circumscribing the lens-forming surface that is sized to be complementarily received within a portion of the interior periphery of the ring, and a base having dimensions greater than the interior periphery; and    c. a rear mold formed of a plastic and having a lens-forming surface, a rim circumscribing the lens-forming surface that is sized to be complementarily received within a portion of the interior periphery of the ring, and a flange having dimensions greater than the interior periphery, 
 wherein when the edge of the front mold and the rim of the rear mold are both received by the ring, the lens-forming surfaces of the front and rear molds and the ring form a mold cavity which has dimensions of a desired lens formable therein.  
   
     
     
         2 . The casting device of  claim 1 , wherein the ring is formed of a plastic.  
     
     
         3 . The casting device of  claim 1 , wherein the ring defines a feed opening and a vent opening therethrough in fluid communication with the mold cavity.  
     
     
         4 . The casting device of  claim 3 , wherein, when the front and rear molds are disposed upright, the vent opening is positioned at substantially the top center.  
     
     
         5 . The casting device of  claim 4 , wherein the mold cavity is substantially is substantially circular in plan view and the feed opening is offset from the vent opening between approximately fifteen to sixty degrees.  
     
     
         6 . The casting device of  claim 1 , wherein the ring has opposed ends, wherein the base of the front mold has a contacting surface that is substantially planar, and wherein the contacting surface and one end of the ring abut when the mold cavity is formed.  
     
     
         7 . The casting device of  claim 6 , wherein the lens-forming surface of the front mold is concave and defines a nadir, wherein the nadir tangentially intersects a plane defined by the contacting surface of the base.  
     
     
         8 . The casting device of  claim 7 , wherein the flange of the rear mold has an engaging surface that is substantially planar and wherein the engaging surface and one end of the ring abut when the mold cavity is formed.  
     
     
         9 . The casting device of  claim 8 , wherein the lens-forming surface of the rear mold has an apex so that a plane tangential to the apex is substantially parallel to and spaced apart from a plane defined by the engaging surface, the separation between the plane tangential to the apex and the plane defined by the engaging surface is the back mold apex height.  
     
     
         10 . The casting device of  claim 9 , wherein the ends of the ring are spaced apart by a ring height, the ring height being the sum of the back mold apex height and a desired center thickness for the mold cavity.  
     
     
         11 . The casting device of  claim 8 , wherein the lens-forming surface of the front mold further comprises a plurality of protrusions each located adjacent the edge, the protrusions having a height corresponding to a desired edge thickness for the mold cavity.  
     
     
         12 . The casting device of  claim 1 , wherein the front mold is rotatable relative to the rear mold so that the two molds are at one of a plurality of selected rotational orientations relative to each other so as to alter characteristics of the mold cavity when the lens-forming surfaces of the respective front and rear molds have asymmetric curvature.  
     
     
         13 . The casting device of  claim 12 , further comprising means for aligning the front and rear molds at a predetermined rotational orientation relative to each other.  
     
     
         14 . The casting device of  claim 13 , wherein the aligning means comprises axis marks on the ring intermediate its opposed ends and an axis-positioning indicator on at least one of the front mold or the rear mold.  
     
     
         15 . The casting device of  claim 1 , wherein the ring and the front and rear molds are movable between a stored position, in which the molds and ring are each spaced apart from each other, and a molding position, in which the ring receives the edge of the front mold and receives the rim of the rear mold to form the mold cavity.  
     
     
         16 . The casting device of  claim 15 , wherein, when in the stored position, the rear mold is selected from a group of rear molds, in which different rear molds form mold cavities having different dimensions when in the molding position.  
     
     
         17 . The casting device of  claim 15 , wherein, when in the stored position, the ring is selected from a group of rings, in which different rings have their respective opposed ends spaced apart at different heights to form mold cavities having different dimensions when in the molding position.  
     
     
         18 . The casting device of  claim 15 , wherein the lens-forming surface of the front mold further comprises a plurality of protrusions each located adjacent the edge, wherein, when in the stored position, the front mold is selected from a group of front molds that have protrusions of a height different from other front molds.  
     
     
         19 . The casting device of  claim 15  wherein, when in the molding position, the front mold is rotatably movable relative to the rear mold so that the two molds are at one of a plurality of selected rotational orientations relative to each other so as to alter characteristics of the mold cavity when the lens-forming surfaces of the respective front and rear molds have asymmetric curvature relative to each other.  
     
     
         20 . The casting device of  claim 1 , further comprising a fill bag having an interior and an injection port detachably connectable to the feed opening, wherein when the port is connected to the feed opening, a fluid located within the interior of the fill bag may traverse through the injection port and into the mold cavity.  
     
     
         21 . The casting device of  claim 1 , further comprising monomer disposed within the mold cavity.  
     
     
         22 . The casting device of  claim 1 , wherein the plastic forming the front and rear molds comprises polymethylmethacrylate.  
     
     
         23 . The casting device of  claim 1 , wherein the lens-forming surfaces of the front and rear molds are coated with a composition that transfers in situ to a lens when formed within the mold cavity.  
     
     
         24 . A casting device, comprising: 
 a. a ring having an interior periphery;    b. a front mold formed of a plastic and having a lens-forming surface, an edge circumscribing the lens-forming surface that is sized to be complementarily received within a portion of the interior periphery of the ring, and a base having dimensions greater than the interior periphery;    c. a rear mold formed of a plastic and having a lens-forming surface, a rim circumscribing the lens-forming surface that is sized to be complementarily received within a portion of the interior periphery of the ring, and a flange having dimensions greater than the interior periphery; and    d. means for injecting a fluid into the mold cavity, 
 wherein when the edge of the front mold and the rim of the rear mold are both received by the ring, the lens-forming surfaces of the front and rear molds and the ring form a mold cavity which has dimensions of a desired lens formable therein.  
   
     
     
         25 . The casting device of  claim 24 , wherein the injecting means comprises: 
 a. a feed opening defined through the protrusion of the rear mold and in fluid communication with the mold cavity; and    b. a vent opening defined through the protrusion of the rear mold, wherein the vent opening is in fluid communication with the mold cavity and ambient to allow fluid flow therethrough.    
     
     
         26 . The casting device of  claim 25 , wherein, when the front and rear molds are disposed upright, the mold cavity is substantially circular in plan view, the vent opening is positioned at substantially the top center, and the feed opening is offset approximately fifteen to sixty degrees therefrom.  
     
     
         27 . The casting device of  claim 24 , further comprising means for positioning the front and rear molds at a predetermined axial separation distance to obtain a desired center thickness within the mold cavity.  
     
     
         28 . The casting device of  claim 24 , further comprising means for aligning the front and rear molds at a predetermined rotational orientation relative to each other.  
     
     
         29 . The casting device of  claim 25 , further comprising: 
 a. a fill bag having an interior; and    b. means for detachably connecting the feedbag to the feed opening for allowing a fluid located within the interior of the fill bag to traverse into the mold cavity.    
     
     
         30 . The casting device of  claim 24 , further comprising means for orienting the front and rear molds at a predetermined rotational position with respect to each other.  
     
     
         31 . The casting device of  claim 24 , wherein the plastic forming the front and rear molds comprises polymethylmethacrylate.  
     
     
         32 . The casting device of  claim 24 , wherein the lens-forming surfaces of the front and rear molds are coated with a composition that transfers in situ to a lens when formed within the mold cavity.  
     
     
         33 . The casting device of  claim 24 , wherein the injecting means injects monomer into the mold cavity.  
     
     
         34 . A casting component, comprising: 
 a casting mold formed of a plastic, the mold having a lens-forming surface, a border circumscribing the lens-forming surface, and a backing member    wherein the border of the lens-forming surface is sized to be complementary received within an interior periphery of a ring to form a substantially fluid-tight seal therebetween,    wherein the backing member is sized to abut an end the ring when the border is received within its interior periphery,    wherein, when the backing member abuts end of the ring, the interior surface of the casting mold and the interior periphery of the ring define a portion of a mold cavity, in which the mold cavity has dimensions to form a desired lens therein.    
     
     
         35 . A method of casting a lens, comprising: 
 a. joining a ring, a front mold, and a rear mold together to form a mold cavity therebetween having dimensions of a desired lens formable therein, the molds each having a backing member, a portion of the front and rear molds being received by an interior periphery of the ring until the respective molds each abut an opposed end of the ring;    b. injecting a lens-forming fluid into the mold cavity and simultaneously venting displaced fluid from the mold cavity to ambient;    c. curing the lens-forming fluid within the mold cavity to form a lens having dimensions substantially the same as mold cavity; and    d. separating the cured lens from the ring and molds.    
     
     
         36 . The method of  claim 35 , wherein the front and rear molds are formed of a plastic.  
     
     
         37 . The method of  claim 36 , wherein the plastic is polymethylmethacrylate.  
     
     
         38 . The method of  claim 35 , wherein the lens-forming fluid is monomer.  
     
     
         39 . The method of  claim 35 , wherein photo curing is used to harden the lens-forming fluid.  
     
     
         40 . The method of  claim 35 , wherein the front and rear molds are rotatably movable relative to each other to one of a plurality of rotational orientations.  
     
     
         41 . The method of  claim 35 , wherein the ring and molds have dimensions so that when joined together, the mold cavity has a desired center thickness.  
     
     
         42 . The method of  claim 41 , wherein the ring and molds are selected from a plurality of molds that collectively form the desired center thickness when coupled together.  
     
     
         43 . The method of  claim 35 , wherein before joining the ring and molds together, substantially all of the surfaces of the front and rear molds that define the mold cavity are coated with a composition that transfers in situ to the lens formed within the mold cavity.  
     
     
         44 . The method of  claim 35 , wherein the formed lens is a spectacle lens.